1. Field of Invention
The present invention relates to a pattern formation method, a method for resist underlayer film formation, a composition for resist underlayer film formation, and a resist underlayer film.
2. Description of the Related Art
In manufacture of integrated circuit devices, multilayer resist processes have been employed these days for attaining higher integrity. In brief, according to the multilayer resist process, a resist pattern is obtained by: applying a composition for resist underlayer film formation first on a substrate to be processed to form a resist underlayer film; applying a resist composition thereon to form a resist coating film; and then transferring a mask pattern on the resist coating film and developing in an appropriate developer using a stepper, etc. Thereafter this resist pattern is transferred on the resist underlayer film by dry etching. Finally, the resist underlayer film pattern is transferred to the substrate to be processed by dry etching, whereby a substrate on which a desired pattern is formed can be obtained.
In the aforementioned multilayer resist process, further miniaturization of the pattern to be formed has been enhanced, and thus there exist demands for additional improvement of the pattern transfer performance and etching resistance of the resist underlayer film. To meet such demands, various investigations for structures of and functional groups included in polymers which may be contained in compositions for forming a resist underlayer film have been carried out (see JP-A No. 2004-177668).
On the other hand, along with miniaturization of formed pattern, RIE (Reactive Ion Etching) has been in widespread use as the aforementioned dry etching process; therefore, disadvantages of occurrence of deformation such as bending or forming a corrugated shape of the underlayer film pattern have been marked during etching a substrate to be processed using a resist underlayer film as a mask. When the resist underlayer film is deformed, deterioration of the pattern transfer performance on the substrate to be processed is obliged. In this regard, improvement of bend resistance by introducing an alkylthienyl group to a polymer that forms a resist underlayer film was reported (see JP-A No. 2010-107790). However, this technique is disadvantageous in that sulfur components in outgas increases during formation of a resist underlayer film, thereby leading to increase of the odor.